Assessment of right ventricular function by isovolumic acceleration of pulmonary and tricuspid annulus in surgically repaired tetralogy of Fallot.

Assessment of right ventricular (RV) function is quite important in patients with surgically corrected tetralogy of Fallot (TOF). However, quantitative assessment of RV function remains challenging, mainly because of the complex RV geometry. This prospective study investigated isovolumic acceleration (IVA), a parameter of myocardial systolic function not influenced by either preload or afterload, using tissue Doppler imaging. We evaluated IVA measured on pulmonary annulus (PA-IVA) and tricuspid annulus (TA-IVA), because we considered that PA-IVA and TA-IVA correspond with systolic function of the RV outflow tract (RVOT) and RV basal function, respectively. Thirty-nine patients with surgically repaired TOF (TOF group) and 40 age-matched healthy children (control group) were enrolled in this study. No significant difference was seen between TA-IVA (2.5 ±â€…0.8 m/s2) and PA-IVA (2.4 ±â€…0.8 m/s2) in the control group. In the TOF group, PA-IVA (1.0 ±â€…0.5 m/s2) was significantly lower than TA-IVA (1.3 ±â€…0.6 m/s2, p < 0.05). Both TA-IVA and PA-IVA were significantly lower in the TOF group than in the control group (p < 0.05 each). We concluded that PA-IVA offers a useful index to assess RVOT function in TOF patients. J. Med. Invest. 67 : 145-150, February, 2020.

3D-assessment of RVOT dimensions prior percutaneous pulmonary valve implantation: comparison of contrast-enhanced magnetic resonance angiography versus 3D steady-state free precession sequence.

To compare contrast-enhanced magnetic resonance angiography (ceMRA) and 3D steady-state free precession (SSFP) during systole and diastole for assessment of the right ventricle outflow tract (RVOT) in patients considered for percutaneous pulmonary valve implantation (PPVI) after tetralogy of Fallot (TOF) repair. We retrospectively evaluated 89 patients (male: 45, mean age 19 ± 8 years), who underwent cardiac-MRI after surgical TOF-repair. Datasets covering the whole heart in systole and diastole were acquired using ECG-gated 3D SSFP and non-gated ceMRA. Measurements were performed in SSFP-sequences and in ceMRA in the narrowest region of the RVOT to obtain the minimum, maximum and effective diameter. Invasive balloon sizing as the gold standard was available in 12 patients. The minimum diameter in diastolic SSFP, systolic SSFP and ceMRA were 21.4 mm (± 6.1 mm), 22.6 mm (± 6.2 mm) and 22.6 mm (± 6.0 mm), respectively. Maximum diameter was 29.9 mm (± 9.5 mm), 30.0 mm (± 7.0 mm) and 28.8 mm (± 8.1 mm) respectively. The effective diameter was 23.2 mm (± 5.7 mm), 27.4 mm (± 6.7 mm) and 24.4 mm (± 6.2 mm), differing significantly between diastole and systole (p < 0.0001). Measurements in ECG-gated SSFP showed a better inter- and intraobserver variability compared to measurements in non-ECG-gated ceMRA. Comparing invasive balloon sizing with our analysis, we found the highest correlation coefficients for the maximum and effective diameter measured in systolic SSFP (R = 0.99 respectively). ECG-gated 3D SSFP enables the identification and characterization of a potential landing zone for PPVI. The maximum and effective systolic diameter allow precise sizing for PPVI. Patients with TOF-repair could benefit from cardiac MRI before PPVI.

Percutaneous Versus Surgical Pulmonic Valve Implantation for Right Ventricular Outflow Tract Dysfunction.

BACKGROUND/PURPOSE: Percutaneous pulmonic valve implantation (PPVI) is an alternative treatment strategy to surgical pulmonic valve implantation (SPVI) for right ventricular outflow tract (RVOT) dysfunction. This study sought to compare outcomes of both treatment strategies. METHODS: The study population was extracted from the 2014 Nationwide Readmissions Database (NRD) using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for PPVI and SPVI. Study outcomes included all-cause in-hospital mortality, length of index hospital stay (LOS), post-procedural bleeding, mechanical complications of heart valve prosthesis, vascular complications (VC), infective endocarditis (IE), total hospitalization charges, and 30-day readmission rates. RESULTS: A total of 975 patient discharges (176 in PPVI and 799 in SPVI group) were identified (average age 25.7 years; 57.5% male). PPVI was associated with significantly shorter median LOS (1 versus 5 days, p < 0.01), lower risk of bleeding (4.6% versus 26.4%, p < 0.01), and lower total hospitalization charges ($169,551.7 versus $210,681.8, p = 0.02). There was no significant difference between both groups in terms of all-cause in-hospital mortality (0% versus 1.4%, p = 0.12), mechanical complications of heart valve prosthesis (1.7% versus 2.0%, p = 0.78), VC (2.3% versus 2.0%, p = 0.82), IE (1.7% versus 3.1%, p = 0.31), or 30-day readmission rates (4.4% versus 7.6%, p = 0.16). CONCLUSION: Compared with SPVI, PPVI was associated with shorter LOS, lower bleeding, and lower total charges. There was no significant difference between the two strategies in terms of all-cause in-hospital mortality, mechanical complications of heart valve prosthesis, VC, IE, or 30-day readmission rates.

Radiofrequency perforation of the pulmonary valve: an efficient low cost solution.

Objective The aim of the study was to assess the feasibility of using commonly available catheterization laboratory equipment for radiofrequency perforation of the pulmonary valve in patients with pulmonary atresia and intact ventricular septum. Methods The system (off-label use for all items) is made up of a co-axial telescopic arrangement consisting of a 0.014" PT 2 ™ coronary guidewire, for insulation inside a 2.7-F microcatheter which has an inner lumen of 0.021". The microcatheter was passed via a standard 4-F right coronary catheter to just below the atretic pulmonary valve. Radiofrequency (RF) energy was delivered using a standard electrosurgical system. In vitro testing had been performed and indicated that 5-10 W for 2-5 s would be sufficient for valve perforation. Results Radiofrequency perforation was successfully performed in all (n = 5, 100%) patients at a median age of 3 days (range: 1-36) and weight 2.7 kg (range 2.3-3.0). In one patient the pericardium was entered during the initial attempt; the generator was put on coagulation mode during retrieval of the guidewire and no haemopericardium occurred. The pulmonary valve was dilated in all; in three patients (n = 3) the ductus arteriosus was stented during the same session. Conclusion Results of the study show that it is feasible to perforate the pulmonary valve safely using this system. Availability, simplicity and cost are noteworthy benefits.

Pulmonary valve replacement and quality-of-life assessment.

BACKGROUND: Chronic pulmonary regurgitation is common after repair of tetralogy of Fallot. Despite the deleterious effects of chronic pulmonary regurgitation on right ventricular function, many patients with repaired tetralogy of Fallot remain asymptomatic. Health is defined not only by the absence of disease but also by physical, mental, and social wellbeing. We sought to examine the impact of pulmonary valve replacement on quality of life in asymptomatic patients with repaired tetralogy of Fallot and chronic pulmonary regurgitation. METHODS: From January 2009 to December 2012, 25 (18 male) asymptomatic patients (mean age 23.4 ± 7.4 years) who underwent pulmonary valve replacement for significant pulmonary regurgitation were recruited. Cardiac magnetic resonance was performed pre- and postoperatively. Quality of life was assessed using the Chinese version of the SF-36v2 evaluation tool. Demographics, clinical data, magnetic resonance findings, and quality-of-life scores were collected and calculated for comparison. RESULTS: After surgery, the indexed right ventricular end-diastolic volume (193 ± 47.3 vs. 105.6 ± 29.6 mL m(-2), p < 0.001) and indexed right ventricular end-systolic volume (108.5 ± 32.9 vs. 61.1 ± 23 mL m(-2), p < 0.001) decreased significantly. The response rates for pre- and postoperative quality-of-life assessments were 100%. Patients demonstrated improvements in all 8 domains of the SF-36v2 assessment. The physical (46.5 ± 6.6 vs. 49.9 ± 6.4, p = 0.012) and mental (43.7 ± 7.8 vs. 51.9 ± 7.6, p < 0.001) component summary scores increased after surgery. CONCLUSION: Pulmonary valve replacement can improve the quality of life in patients with chronic asymptomatic pulmonary regurgitation.

Evaluation of the Melody transcatheter pulmonary valve and Ensemble delivery system for the treatment of dysfunctional right ventricle to pulmonary artery conduits.

Synthetic conduits and bioprosthetic valves are used in the treatment of patients with congenital heart disease involving the right ventricular outflow tract and pulmonary valve. In-situ time-dependent degradation uniformly results in conduit and valve dysfunction. The abnormal hemodynamics imposed by valve and conduit dysfunction have been linked to exercise intolerance, arrhythmia, right heart failure, and sudden death. Starting in childhood, affected patients are subjected to repeated open-heart surgeries to restore valve function and potentially reduce morbidity and mortality. Percutaneous transcatheter pulmonary valve replacement with the Melody Transcatheter Pulmonary Valve (Medtronic, Inc., Minneapolis, MN) has been performed in ≈8000 patients worldwide. The valve and implant procedure provide a far less invasive means of restoring valve and conduit function and allow patients to forego multiple operations. Recent clinical trials have shown excellent and durable results in terms of valve function, relief of obstruction, and improvement in functional class up to 7 years from implant.

Multivariable assessment of the right ventricle by echocardiography in patients with repaired tetralogy of Fallot undergoing pulmonary valve replacement: a comparative study with magnetic resonance imaging.

BACKGROUND: Evaluation of the right ventricle (RV) using transthoracic echocardiography is challenging in patients with repaired tetralogy of Fallot (rTOF). AIMS: To evaluate the accuracy of conventional echocardiographic variables and real-time three-dimensional echocardiography (RT3DE) in assessing right ventricular (RV) volumes and function compared with magnetic resonance imaging (MRI), in adult patients with rTOF and referred for pulmonary valve replacement (PVR). METHODS: Complete echocardiography was performed on 26 consecutive patients referred for PVR, before and 1 year after surgery. All variables were compared with MRI. RESULTS: Correlations between conventional variables and MRI were absent or poor when assessing RV ejection fraction (RVEF), except for fractional area of change (FAC; r=0.70, P<0.01 before PVR; r=0.68, P<0.01 after PVR) and RT3DE (r=0.96, P<0.01 before PVR; r=0.98, P<0.01 after PVR). The RV volume correlation between RT3DE and MRI was excellent before and after surgery for RV end-diastolic volume (r=0.88, P<0.01 and r=0.91, P<0.01, respectively) and RV end-systolic volume (r=0.92, P<0.01 and r=0.95, P<0.01, respectively). The accuracy of these indices, as a diagnostic test for impaired RV (<45%), was good: Youden's indexes varied from 0.47 to 0.89; areas under the receiver operating characteristic curve before and after PVR were 0.86 and 0.81 for FAC and 0.98 and 0.97 for RT3DE, respectively. CONCLUSION: Commonly used echocardiography variables, such as tricuspid annular plane systolic excursion and tricuspid annular peak systolic velocity, did not sensitively evaluate global RVEF. A global approach, that includes the whole RV and integration of its different components, was more reliable in patients with rTOF.

Percutaneous pulmonary valve endocarditis: incidence, prevention and management.

The epidemiology of infective endocarditis is changing rapidly due to the emergence of resistant microorganisms, the indiscriminate use of antibiotics, and an increase in the implantation of cardiovascular devices including percutaneous valves. Percutaneous pulmonary valve implantation has achieved standard of care for the management of certain patients with right ventricular outflow tract dysfunction. With its expanding use, several cases of early and delayed infective endocarditis with higher morbidity and mortality rates have been reported. This review summarizes the trends in percutaneous pulmonary valve infective endocarditis, postulates proposed mechanisms, and elaborates on the prevention and management of this unique and potentially fatal complication.

Functional and haemodynamic assessment of mild-to-moderate pulmonary valve stenosis at rest and during exercise.

OBJECTIVE: In adult patients with mild-to-moderate pulmonary valve (PV) stenosis, exercise capacity and haemodynamics have not been extensively studied, although regular exercise is recommended. Therefore, we aimed to assess exercise capacity to study the increase in PV gradient during exercise and to evaluate the impact of this increased pressure load on the RV. METHODS: Nineteen patients (8 female; 29±6.4 years) with isolated mild-to-moderate PV stenosis and no prior cardiac interventions were consecutively enrolled from the outpatient clinic of adult congenital heart disease. All patients underwent cardiopulmonary exercise testing, transthoracic echocardiography and bicycle stress echocardiography. Results for exercise testing were compared with age-matched and gender-matched control patients. RESULTS: In the studied population, resting heart rate (89±11 vs 75±14 bpm; p=0.001), peak power (199±66 vs 263±68 W; p=0.006); peak VO2 (31.2±9.9 vs 39±7.4 mL/kg/min; p=0.011); oxygen uptake efficiency slope (2430±913 vs 3292±943(mL/min)/(L/min); p=0.007) and VE/VCO2 slope (26.8±5.2 vs 22.6±4.3; p=0.01) differed significantly from controls. A linear increase of peak PV gradient with increasing flow was observed in the pooled dataset (Pearson's R=0.947; p<0.0001) and slopes identical as for control patients were obtained for the oxygen pulse-workload relationship. Right heart morphology and function were preserved in the studied patients. CONCLUSIONS: Patients with mild-to-moderate PV stenosis have decreased exercise capacity. A linear increase in PV gradient with flow suggests a fixed valve area throughout the exercise. Although systolic RV pressure load increases during exercise, good ventricular performance was observed without signs of functional or morphological changes of the right heart. CLINICAL TRIAL NUMBER: NCT01444222.

Doppler echocardiographic assessment of pulmonary prostheses: a comprehensive assessment including velocity time integral ratio and prosthesis effective orifice area.

OBJECTIVE: Few reports have been published on the Doppler-derived echocardiographic data for pulmonary valve prostheses (PVPs). The aim of this study was to provide a comprehensive Doppler echocardiographic assessment of PVPs. METHODS: We studied 40 patients (mean age 24.2) with PVPs: 13 (32.5%) mechanical and 27 (67.5%) bioprosthetic valves. After clinical evaluation, all patients underwent complete, two-dimensional and Doppler studies. RESULTS: In 30 patients with normally functioning PVPs, the mean (SD) peak velocity was 2.33 (0.36) m/s with an average peak pressure gradient of 22.69 (6.7) mm Hg and an average mean pressure gradient of 12.5 (4.1) mm Hg. The mean PVPs velocity time integral (VTI) was 47.49 (12.78) cm with mean right ventricle outflow tract/peak velocity (PV) VTI ratio 0.43 (0.14), mean PVPs effective orifice area was 1.63 (0.36) cm(2). Metallic PVPs had significantly better hemodynamic Doppler study compared with biologic PVPs. In 9 patients with PVP malfunction, average peak PVPs velocity, average peak pressure gradient, mean pressure gradient, PV VTI, PV/left ventricle outflow tract VTI ratio was significantly increased (P < 0.05). CONCLUSION: This study contributes to establishing the normal range for Doppler hemodynamics in various PVPs.

The assessment of pulmonary hypertension.

The goals of evaluating pulmonary hypertension are detection, definition of severity and the nature of the hemodynamic lesion and its consequences, diagnosis of causal or associated conditions, and determination of optimal therapy. These objectives are reliably achieved by a disciplined approach employing multiple diagnostic tools. This chapter outlines the fundamental background and guidelines for assessing pulmonary hypertension, including consideration of several new and less frequently used methods to elucidate the physiologic mechanism. Since early detection and treatment may improve outcome, screening higher risk populations and a diagnostic approach to the milder spectrum of pulmonary hypertension is also addressed.

[Doppler echocardiographic assessment of left ventricular diastolic function in dogs]. / Zur Doppler-echokardiographischen Beurteilung der linksventrikulären diastolischen Herzfunktion beim Hund.

Pulmonary venous flow velocity pattern, transmitral flow pattern, isovolumic relaxation time, and left ventricular fractional wall thinning were analyzed in 72 dogs with heart disease by transthoracic Doppler and M-mode echocardiography and compared with other noninvasive variables of left ventricular and left atrial systolic performance. Abnormal diastolic blood flow was found in 49 (68%) dogs, predominantly flow patterns suggestive of relaxation abnormality and increased filling pressures. Diastolic flow abnormalities despite normal systolic performance were found in 23 (32%) dogs of which 14 (61%) revealed clinical signs of heart disease. The diagnostic sensitivity of pulmonary venous flow parameters for echocardiographically detectable diastolic disturbance was found to be higher compared with the other noninvasive parameters of diastolic heart function measured. Diastolic filling pattern appear to correlate closer with functional status in many dogs with heart disease than indices of systolic performance.

Long-term assessment of right ventricular diastolic filling in patients with pulmonic valve stenosis successfully treated in childhood.

Patients with severe pulmonic stenosis (PS) have right ventricular (RV) diastolic filling abnormalities detectable by tricuspid valve pulsed Doppler examination. To determine if these abnormalities persist long term after successful therapy of PS, 19 patients were examined 8 +/- 3 years after PS therapy. At the time of follow-up Doppler examination, the PS gradient was 15 +/- 8 mm Hg. From the tricuspid valve inflow Doppler study, the following measurements were obtained at peak inspiration: peak velocities at rapid filling (peak E) and during atrial contraction (peak A), ratio of peak E to peak A velocities, RV peak filling rate normalized for stroke volume, deceleration time, the fraction of filling in the first 0.33 of diastole as well as under the E and A waves, and the ratio of E to A area. Data from PS follow-up patients were compared with our previously reported data from 12 age-related control subjects and 14 untreated patients with PS. Patients with PS who were followed up had higher peak E velocity (0.75 +/- 0.14 vs 0.59 +/- 0.21 m/s), lower peak A velocity (0.47 +/- 0.09 vs 0.64 +/- 0.28 m/s), higher E/A velocity ratio (1.65 +/- 0.33 vs 1.11 +/- 0.52), higher 0.33 area fraction (0.52 +/- 0.08 vs 0.34 +/- 0.14), lower A area fraction (0.29 +/- 0.06 vs 0.45 +/- 0.21) and higher E/A area ratio (2.48 +/- 0.82 vs 1.73 +/- 1.05) than PS patients without treatment (p less than 0.03). All Doppler indexes of the patients with PS who were followed up were the same as those of the control subjects except for the peak E velocity that was slightly higher (0.75 +/- 0.14 vs 0.63 +/- 0.11 m/s), the peak A velocity that was slightly higher (0.47 +/- 0.09 vs 0.38 +/- 0.09 m/s) and the E/A area ratio that was slightly lower (2.48 +/- 0.82 vs 3.50 +/- 1.25) (p less than 0.03). Thus, at long-term follow-up, all RV diastolic filling indexes in successfully treated patients with PS improved compared with the untreated patients and approached values found in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive assessment of hemodynamic responses to exercise in pulmonary regurgitation after operations to correct pulmonary outflow obstruction.

The influence of pulmonary regurgitation (PR) on exercise capacity is unknown. The hemodynamic responses to exercise in postoperative patients with PR was determined using Doppler-measured regurgitant fraction to indicate PR severity. Maximal heart rate, oxygen consumption and workload capacity were measured during upright cycle ergometry. Cardiac output was measured at rest and during submaximal supine cycle ergometry by pulsed Doppler echocardiography. Oxygen consumption was simultaneously measured and exercise factor was calculated as the change in cardiac output per change in oxygen consumption. Twenty-seven patients were compared with 17 age-, size- and sex-matched control subjects. Patients with PR had larger right ventricles (p less than or equal to 0.001), lower heart rate response (p less than or equal to 0.05), lower maximal oxygen consumption (p less than or equal to 0.005) and lower workloads (p less than or equal to 0.005) when compared with normal control subjects during maximal exercise testing. Exercise factor was the same for both groups. Patients with PR were then separated into mild, moderate and severe groups. Patients with mild PR had a normal response to exercise. However, patients with moderate and severe PR had lower maximal oxygen consumptions and maximal workloads than control subjects. Control, mild and moderate PR groups had similar exercise factors. Patients with severe PR had markedly low cardiac output responses. PR is associated with reduced exercise capability, which is related to the severity of the PR.

Increased blood velocities in the heart and great vessels of patients with congenital heart disease. An assessment of their significance in the absence of valvar stenosis.

During a previous investigation and during routine clinical Doppler echocardiography velocities distal to normal valves were found to be increased in patients with congenital heart disease. To investigate this observation the velocity proximal and distal to cardiac valves was recorded in 56 patients with congenital heart disease. No detectable pressure gradient had been found across these valves at catheterisation and no velocity gradient greater than 20 cm/s was found across them by range gated Doppler echocardiography. In 82% of the patients, however, the blood velocity across one or more valves exceeded normal limits. Increased velocities were found at the tricuspid inflow (55%), pulmonary artery (38%), mitral inflow (34%), and ascending aorta (11%). Factors predisposing to the presence of increased velocities in these areas were increased flow through the valve and decreased compliance of the receiving chamber. This study shows the necessity for recording velocity both proximal and distal to a valve before a gradient is calculated according to the modified Bernouilli equation.

The pulmonic valve echogram in the assessment of pulmonary hypertension in children.

Echocardiographic patterns of pulmonary valve motion and right-sided systolic time intervals were correlated with pulmonary arterial hemodynamics in 56 children with congenital heart defects. The sensitivity of an abnormal a-dip, reduced e-f slope or mid-systolic valve closure in detecting elevated pulmonary artery diastolic or mean pressures or pulmonary to systemic resistance ratio varied from 36 to 62%. Specificities ranged from 50% (e-f slope for increased Rp:Rs) to 93% (mid-systolic closure for PA diastolic pressure greater than 10 mm Hg). Systolic-time-intervals (RPEP/RVET) did not significantly correlate with pulmonary hemodynamics. We therefore conclude that these echocardiographic features are insufficiently sensitive to be clinically applied to detect pulmonary hypertension in pediatric patients, and that only 2 (a-dip and mid-systolic closure) were of sufficient specificity to be useful.

Noninvasive radiographic assessment of cardiovascular function in acute and chronic respiratory failure.

Noninvasive radiographic techniques have provided a means of studying the natural history and pathogenesis of cardiovascular performance in acute and chronic respiratory failure. Chest radiography, radionuclide angiocardiography and thallium-201 imaging, and M mode and cross-sectional echocardiography have been employed. Each of these techniques has specific uses, attributes and limitations. For example, measurement of descending pulmonary arterial diameters on the plain chest radiograph allows determination of the presence or absence of pulmonary arterial hypertension. Right and left ventricular performance can be evaluated at rest and during exercise using radionuclide angiocardiography. The biventricular response to exercise and to therapeutic interventions also can be assessed with this approach. Evaluation of the pulmonary valve echogram and echocardiographic right ventricular dimensions have been shown to reflect right ventricular hemodynamics and size. Each of these noninvasive techniques has been applied to the study of patients with respiratory failure and has provided important physiologic data.

Assessment of pulmonary valve echogram in normal subjects and in patients with pulmonary arterial hypertension.

To assess the validity of ultrasound criteria for pulmonary arterial hypertension, we studied pulmonary valve motion in 28 patients and 20 normal subjects. In the latter group, we categorised normal movement of the posterior leaflet of the pulmonary valve in a fashion not previously described. Of the 28 patients, 19 had pulmonary arterial hypertension (pulmonary artery mean pressure more than 20 mmHg, range 22 to 72). Negative, flat, and positive e to f slopes occurred equally in normal subjects and patients. Maximal a wave excursion was less than 2 mm in 9 of 13 patients with pulmonary hypertension who had sinus rhythm, but was more than 2 mm in all normals and in the 9 patients with normal pulmonary artery pressure (69% sensitivity and 100% specificity). The b to c slope was more than 450 mm/s in 6 of 18 patients with pulmonary arterial hypertension and was less than 450 mm/s in all others (33% sensitivity and 100% specificity). The normalised right ventricular pre-ejection period was more than 0.095 (range 0.10 to 0.16) in 13 of the 19 patients with pulmonary arterial hypertension and less than 0.095 in all others (68% sensitivity and 100% specificity). A midsystolic notch occurred in patients with pulmonary arterial hypertension and in no normal subjects or patients with normal pulmonary arterial pressure. Of the 19 patients with pulmonary arterial hypertension, 18 were identified by one or more ultrasound criteria. Of the 5 patients who met only 1 criterion (increased normalised right ventricular pre-ejection period), 4 had atrial fibrillation. We conclude that measurement of the pulmonary valve e to f slope is useless for identifying pulmonary arterial hypertension. However, changes in normalised right ventricular pre-ejection, maximal a wave excursion, b to c slope, and the presence of a midsystolic notch, while insensitive, are highly specific for pulmonary atrial hypertension.

[Echocardiography. Advantages and limitations related to unidimensional and bidimensional technics in real time]. / L'échocardiographie. Avantages et limitations respectifs des techniques unidimensionnelle et bidimensionnelle en temps réel.

Mode-M echocardiography is the most valuable non invasive technique in cardiology, but as a one-dimensional technique it displays the cardiac structure in an unfamiliar form without resemblance to the cardiac anatomy. Two-dimensional ultrasonic imaging of the heart overcomes this disadvantage. However, the definition of these scanners leaves much to be desired and becomes very poor when the stop-frame mode is used. The major disadvantages of the "multiscan" are the length of the multicrystal transducer, distortion of the picture, spurious echoes and verticalization. The sector scanner has smaller transducers fitting the "echocardiographic window" and permitting an apical, subxiphoid and suprasternal approach. However, with this system resolution is usually poor in the first anterior 3.5--4 cm after the thoracic wall. The mechanical scanner causes a vibrating sensation occasionally irritating to the patient. The electronic sector scanner has the widest angle and provides the best quality images. Unfortunately, its cost is markedly higher than that of other two-dimensional systems.